1. Field of the Invention
The present invention relates to an etchant composition, and methods of patterning a conductive layer and manufacturing a flat panel display device using the same. More particularly, the present invention relates to an etchant composition capable of simultaneously etching aluminum, molybdenum and indium-tin-oxide, and methods of patterning a conductive layer and manufacturing a flat panel display device using the same.
2. Description of the Related Art
Flat panel display devices are generally classified into passive matrix type flat panel display devices and active matrix type flat panel display devices, according to the driving scheme employed in the flat panel display device. An active matrix type flat panel display device incorporates circuitry employing a thin film transistor (TFT). This circuitry is generally used for flat panel display devices such as a liquid crystal display (LCD) devices, organic electroluminescence display devices (OLED), etc. Active matrix type flat panel display devices are advantageous in that they have high resolution and an excellent capability of displaying a moving picture. It is also possible to enlarge the size of the display panel.
In the active matrix type flat panel display device, a TFT having a gate electrode and source/drain electrodes is formed. Also, a plurality of interconnections and a pixel electrode may be formed by patterning respective conductive layers of different conductive materials. For instance, the gate electrode is formed of a predetermined conductive material with low resistivity such as aluminum (Al), molybdenum (Mo) and copper (Cu), or an alloy thereof. In addition, the source/drain electrode may be formed of a conductive material such as Mo, chromium (Cr) and Al, or an alloy thereof. The pixel electrode may be formed as a transparent electrode of indium-tin-oxide (ITO) or indium-zinc oxide (IZO). Furthermore, although any one of the conductive layers may be formed as a single layer, it may alternatively be formed as a multilayer formed of different materials in order to obtain beneficial properties.
However, it is difficult to etch respective conductive layers formed of different materials with the same etchant composition because each of the conductive layers has an etching rate different from each other. In addition, because different etchants for different compositions are used, an etching apparatus for one conductive layer is different from an etching apparatus for another conductive layer. Thus, the etching process for forming the TFT and the plurality of interconnections is complicated, and manufacturing costs and manufacturing time increase. This results in a decreased productivity.
To overcome this problem, many efforts have been made to develop an etchant capable of simultaneously etching conductive layers formed of different materials.
For example, an etchant composition capable of simultaneously etching aluminum (Al) and ITO has been developed. As a result, the etching process is performed simultaneously on the gate electrode and the pixel electrode using the same etchant so that productivity is improved. In addition, an etchant composition capable of simultaneously etching a Mo/AlNd bilayer and a single layer of Mo has been suggested. Therefore, conductive layers of different materials may be etched using the same etchant to form the gate electrode and the source/drain electrodes.
However, an etchant which may simultaneously etch Al, Mo and ITO has not been developed. Therefore, it is impossible to form the TFT and the pixel electrode using the same etchant composition.